Influence of current harmonic on electromagnetic force and forced vibration in converter-fed Canned Permanent Magnet Synchronous Motors

Canned Permanent Magnet Synchronous Motors (CPMSMs) are essential components in vacuum pump systems. The stator can of CPMSMs is susceptible to deformation due to thermal stress and high-frequency harmonic electromagnetic force, leading to potential failure. When the CPMSMs are powered by an inverter power supply, it introduces time harmonic current, exacerbating the thermal stress and harmonic electromagnetic force of the system. Thus, this paper analyzes the effects of low-order current harmonics on the electromagnetic force and forced vibration of the stator can. The analytical formulation for the radial electromagnetic force of the CPMSM is obtained, taking into account the influence of harmonic current. Afterwards, the finite element model was established to investigate the space and time harmonic characteristics of the magnetic field and electromagnetic force of the stator can, and its validity was confirmed through testing on a motor test platform. Finally, modal analysis of the stator can under rated conditions and investigation of mechanical deformation induced by electromagnetic force are carried out through harmonic response analysis. This establishes a theoretical basis for improving the reliability and sealing performance of CPMSMs used in pumps.